Constructing a pvc hoophouse for the home garden

We’ve been talking about a greenhouse since we bought our house. We both would love one, but we still have a number of projects higher up the list than a greenhouse (the barn roof, bathroom remodel, refinishing wood floors, the intermittently leaking chimney, etc.). Still, the idea of extending the growing season is just too good to pass up, and our small raised bed pvc hoops have been so great we decided to try a pvc hoophouse (HH) made from conduit. We purchased the materials and got started earlier this month, and Tuesday began construction in earnest. Here’s the process.

Where?

We have serious groundhog issues, so the HH would need to be within the garden fence. We decided to increase the fenced area slightly on the eastern side of the garden, and sited the HH in the northeast corner of the garden, against the north side fence, to the east of the raised beds, running in a N-S direction.

Site preparation

Our site had previously been worked as a garden bed, and last winter held the hen’s snow dome, so it is level (mostly), and a well drained as any spot in the garden. We held off planting there knowing the HH would be sited there, but finally had to break down and plant our second crop of tomatoes, started especially for the HH, before we’d built it. We only damaged one. But before we could begin, we had to pull up the volunteer pumpkin/squash plants growing there. Oh! The carnage! There was fruit already!

Next, we used large deck screws to construct the2″X’6′ base. Prior to putting the base together, we had measured the location of each rib and screwed conduit clamps in place for holding the hoops in position. The finished size of the base is 8’x16′. One the (southern) door entrance end, we put the 2″x6″ with the 6″ side to the ground to make a sill and provide a nice base for the end wall frame. Note the tomatoes on the right, contrasting with the cardboard under the base on the right in the photo (as weed prevention). Later, we’ll cover the cardboard with mulch.

Hoops

Once the base was completed, it was time to set up the hoops. Because we occasionally get heavy wet snow or big storms with over 16″ of snow, we decided to place the hoops fairly close together. The hoops are relatively inexpensive components compared to the cost of constructing a new HH should this one collapse under snow. We originally planned for 7 ribs, but ended up with 8 ribs at approximately 21″ intervals. We still need to pick up 4 additional pieces of conduit to complete the rib installation.

We wanted the final height to be between 6 1/2′ and 7′ in height, so we set it up and determined we needed to remove 1′ from each conduit –in essence the HH is now constructed from 2-9′ pieces of conduit attached in the center. If we had been able to make the HH a little wider, we would not have needed to trim the conduit, but we just didn’t have the space. If this experiment proves wildly successful, we will probably make space in the future for a wider and probably longer HH.

Once we were certain we liked the height, we tightened the screws holding the conduit in place, making sure the conduit was level with the bottom edge of the baseboard.

Purlins

We found 16′ lengths of 1″x3″ at the lumber store, so we decided to use that for purlins. We attached the side purlins 36″ from the bottom of the baseboard, using 2 self-drilling screws for each rib to minimize torquing. Be sure to pre-drill holes at the ends of the 1″x3″ to prevent splitting. We installed both side purlins and called it a day. We’ll attach the center purlin next, and add the final 2 hoops. Note the tight spacing between the new hoop house and the raised bed with shade cloth on the left. I need to get cardboard for weed control down on that side, too.

To complete

We need to order greenhouse plastic, and later in the season we will put the cover on. I think we will order wiggle wire to attach the plastic at the side purlins, which will allow us to easily roll up the sides to vent the HH in the summer. We also need to frame in the southern end and attach a door. We have a big pile of door possibilities in the barn attic, as well as lots of scrap for this part of the project. Before this we will work on prepping the planting beds in the HH and planting our first crops.

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This entry was posted on July 23, 2008 at 10:23 pm and is filed under gardening, hoophouse, projects. You can follow any responses to this entry through the RSS 2.0 feed.
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14 Responses to “Constructing a pvc hoophouse for the home garden”

When you build the next one(s) you might think about putting the pvc and clamps on the inside so that you can secure the poly to the baseboard without interruption. I’m beginning to get excited about the winter growing season!

Robin, we debated about this as we set it up. I think before we do any more we will move the clamps inside Dan just pointed out all we will need to do is switch the baseboard sides. But not today, as it is raining, YAY!

El, please elaborate on the burying versus fastening? We were planning on wiggle wire to attach it for easy removal, and plan on rolling the side up in the spring. Is burying better than wiggle wire? Will it deter burrowing pests?

It is time to think about greenhouses if they are going to be ready for the fall and winter. I love what you have done and the great instructions. I’m building mine from old windows. I’ll have to line it with plastic for the winter. I”m going to use large black plastic trash cans for heat retention. I’ll fill those and put them on the north side. They will heat up during the day and keep it warm at night. It’s a good way to get shelving in your greenhouse too. Just stack boards on top of the cans.

If you decide to put shade fabric over the top and want to be able to adjust it—-save gallon milk jugs. Fill them with water and attach them to several ends that hang over the side of the greenhouse. The weight will keep it in place but you’ll be able to adjust the screen. Some people attach their jugs with S hooks. Tie a knot in the shade material and just hang the S hook over the knot–it will hold. Add more jugs if you got high winds expected.

This method also works for venting at the top. Sometimes if there isn’t vent, you will get lots of mold. If you want to leave a vent, Poke a few holes in the top of the plastic just over the pvc cross bars. One each side of the hole glue down two pieces of sytrofoam. Run another layer of the plastic length wise across the top of the greenhouse covering the holes. You can tape it down with clear packaging tape–or hold it down with 2 litre bottles attached at intervals along the length of the plastic. If you are interested in doing this—let me know and I’ll tell you how to secure the 2 litre bottle to the top layer.

Hi Ali: Leave 18″ or more extra where the plastic hits the ground, then bury it instead of fastening it. You can attach a pipe to the end of this plastic if you wish (more of your conduit would do it, just staple the plastic to the pipe) and you can roll the plastic up around the pipe to make side vents. Critters don’t want to dig through plastic. My experience with the roll-up side vents is it’s an all-or-nothing thing: I don’t roll it half up, so having a relatively lightweight pipe won’t make much of a difference.

My experience with wiggle wire is that it will stretch if not tear the plastic but it’s great to keep the plastic on our metal hoops (ours is a metal hoophouse). So I wouldn’t necessarily recommend it as something you should use to fasten/unfasten the plastic at the base.

Anna, Thanks for the great tips, I especially like the idea of the the vent at the top. We have shadecloth already we use on our small hoops so that may come in handy, or we may remove the plastic altogether in the summer, don’t know yet what we’ll decide.

El, thanks, it is good to know about the plastic keeping the critters at bay, weve been talking over ideas for critter prevention. Will this help with the snakes in the netting do you think? We’d been planning to put a length of conduit on the plastic for the roll up side vent.

Gosh Ali I hope I never see snakes in my netting ever again. And I only had one vole in my greenhouse, and I caught him with a mousetrap. I was able to harvest my last broccoli in April!!! Yep, January through April from July-planted seeds. I didn’t have huge harvests mind but they were really tasty.

We used 2-10 foot pieces of conduit for each rib, and cut 1′ off each piece of conduit, resulting in a hoop of 18′. The width of the base is 8′, and the height is somewhere between 61/2′-7′ at the center ridge. Check back, I’ll update this once we start on the end walls and put up the plastic. And keep me posted on your project!